1. Field of the Invention
This invention relates to a hockey stick for use in playing hockey. More specifically, the invention relates to a hockey stick having a shaft and a replaceable blade which is firmly affixed to the shaft for play, and which blade is loosened to allow changing of the blade by application of heat to the hockey stick at the juncture of the replaceable blade and the shaft.
2. Description of the Related Art
Hockey sticks for playing the game of hockey historically were made of wood and included a shaft and a blade. More recently, advances in the art have given rise to hockey sticks having components formed of other materials, such as aluminum and composite materials, particularly fiber/resin composites incorporating epoxy and graphite. These newer materials are used because they give rise to advantages in weight and balance of the hockey stick and in its flexural properties. Replaceable blades are another more recent advance, and are generally formed of wood overlaid with a composite material such as fiberglass to strengthen the blade and provide increased durability. Such blades have a shank which is inserted into, and interfits with, a socket formed by an open end of the shaft of known hockey sticks.
Blades must be changed periodically due to wear or damage. In the most widely used configuration, the shank is held within the socket and is thus attached to the shaft by the use of a thermoplastic adhesive, commonly known as a "hot melt" glue. Conventionally, such a hot melt glue is liquefiable at temperatures well above that normally encountered in using a hockey stick. When liquified by application of heat such an adhesive allows removal or installation of a blade, and when allowed to cool, solidifies and adhesively bonds together the shaft and the shank of the blade.
Generally, manufacturers of hockey sticks recommend specific methodologies for heating the shaft of the hockey stick at the location of the hot melt glue-bonded connection at the end of the shaft. Such methodologies feature limiting the maximum temperature of the shaft to a material dependent value which allows liquefaction of the thermoplastic adhesive but is not injurious to the material from which the hockey stick shaft is made. Certain materials, specifically composite materials commonly used in forming the shaft, are susceptible to damage and weakening as a result of heating them to high temperatures, such as may be occasioned by using a flame to heat the shaft in carrying out a blade change, for example.
However, it is often desirable to change a blade quickly, and recommended methods of heating the shaft to effect a blade change take a relatively long time, at least as compared to methods commonly employed by hockey players to heat the end of the shaft. Particularly, during a game, players in a hurry to change a damaged blade, for example, may use a high temperature heat source such as a propane torch or the like, providing a rapid transfer of heat energy to the shaft to facilitate a faster blade replacement.
Composite materials, for example those employing fibrous materials and a resin binder, such as epoxy graphite composite materials of the type commonly used in forming hockey stick shafts, are heated well above the recommended temperature for the material by the application of heat delivered at a very high temperature by a propane torch or the like. Degradation of the structural properties important to strength and flexibility of the shaft often results, and breaking of such hockey sticks along the shaft at such a damaged location has been observed. The dangers attendant a hockey stick breaking in this manner during play are well known. At the least, such a damaged hockey stick may be rendered unusable when it is recognized that the portion of the shaft which receives the blade shank has been damaged, and a tight and reliable union between the shaft and the blade cannot thereafter be accomplished.
Because composite materials as presently used in hockey sticks provide very desirable performance properties, such hockey sticks continue to be used, and damaged, through over-heating, at various levels of play from professional hockey down to neighborhood street hockey, for example. Consequently, it has been recognized that damage caused to composite shafts by over-heating should be mitigated. The objectives of providing a hockey stick using composites having desirable properties and sufficiently low cost, and at the same time, allowing rapid blade changes conventionally made using a high temperature heat source such as a torch or the like, seem desirable and yet mutually exclusive.
The above concerns being recognized, there is a need for a hockey stick shaft for use in a hockey stick of the type having a conventional replaceable blade which provides the advantageous properties of composite materials, yet which allows repeated blade changes through application of heat rapidly and at very high temperatures, such as from a torch for example, to be used. The present invention is directed to this need.